It is likely that at some point in the future, all energy will come from nuclear sources. How far way that is, I wouldn't like to say. However, I would hope that the type of nuclear energy we shall be using at that time will be something other than that which predominates today.
A consequence of climate change concerns has been a development that I'd never imagined to see in a million years - Green groups acting as nuclear energy advocates. The reasoning here seem to be that the risks from climate change are so great and the issue of fossil fuel divestment so urgent, that the risks associated with nuclear energy are insignificant by comparison. I'm not sure I agree with that, but anyway, let's look at the issues involved.
The obvious advantage of nuclear energy is that it provides vastly more energy per kilogram of fuel, than does any fossil fuel. Thus, a relatively small quantity of fuel could, in principle, supply the energy needs of a community for a very long time. I say in principle, because one of the issues of current generation reactors is that they extract only a tiny percentage of the energy in the fuel, which to a certain extent negates that advantage.
Nuclear power stations themselves are relatively clean and environmentally friendly, emitting no smoke or combustion gases. Unlike windfarms they blend well with the landscape, and do not cause noise or other nuisance. One construction work is over, heavy vehicle movements are relatively few.
Their energy output is, by and large, constant and reliable. Although the cost per unit is somewhat higher than for fossil fuel, this is mainly down-to the cost of building the reactor itself, the fuel itself being relatively inexpensive. For this reason, nuclear stations tend to be run at full output 24/7 so as to recoup the best return on the cost of construction.
So far, all that we've said seems very favourable. However, the two major issues with present-day designs are the large amounts of highly radioactive spent fuel the reactors generate in normal operation, and the dire consequences of a reactor getting out of control.
The large amounts of problematic waste are a direct consequence of the first issue mentioned, that only a tiny percentage of the fuel is actually consumed. Way back in the 1950's it was intended to reprocess spent fuel so that it could be used several times over, extracting more of its energy. Unfortunately the reprocessing itself was found to be environmentally polluting, and had to be largely abandoned. Thus, today's reactors use their fuel only once. It is then thrown away. The problem here is that the fuel is by no means exhausted and will continue to release high levels of radiation and heat for at least several hundred years, and lower levels for thousands. This raises the well-known and perplexing question of what to do with the spent fuel.
There are two possible resolutions; to design a reactor which makes more efficient use of its fuel. If 98% of the fuel is turned into useful energy, then only 2% remains as problematic waste. Or, to use a type of reaction whose waste products are shorter-lived, and which therefore do not require such long-term storage. Thorium reactors offer a potential resolution to the issue of low efficiency of fuel usage, whilst fusion may address the storage issue by way of creating shorter-lived reaction products.
Of the reactors so far commissioned, two -Chernobyl and Fukushima- have suffered catastrophic 'level 7' incidents which caused widespread pollution, and three -Windscale, Three Mile Island and Idaho Falls- have suffered very serious incidents which caused local contamination and loss of life or radiation sickness.
Nuclear energy proponents try to play-down these incidents by claiming that they were not as serious as the press would have had the public believe. They may also claim that two or five failures is an insignificant number in over half a century of nuclear energy. I think we quite easily can dismiss these attempts at whitewashing. Face it, Chernobyl was very bad, and only by luck was it not even worse.
There are somewhat over four hundred nuclear generating stations in the world today. That is actually quite a surprisingly small number. Each station may have more than one reactor, for example Chernobyl had two and Fukushima Daichi, four. Nevertheless a catastrophic failure rate of two in four hundred stations is 0.5%, and a failure rate as high as that would never be tolerated in, for example, aviation. When you look at it like that, it is less acceptable.
We'll look at these nuclear accidents in more detail on following pages, but for them moment, the surprising point emerges that the most serious of the incidents resulted from chemical fires or steam explosions which followed on as a consequence of a runaway of the nuclear process. In only one major incident, Idaho Falls, was the nuclear reaction itself responsible directly for the catastrophe, and no pollution was released by that incident. What this tells us is a very simple and straightforward message: Nuclear processes are relatively safe, but reactor vessels containing inflammable chemicals or high pressures are NOT safe.
The way towards a safer nuclear industry is therefore to adopt reactor designs which contain no inflammable substances, and no boiling liquids under high pressure.
Unfortunately, the contractors we presently engage are heavily focused on the PWR/BWR concept. They themselves recognise the inherent safety issues of this design, and therefore build-in numerous safety devices in an attempt to forestall the likelihood of a radiation release in the event of any loss of control. This has the consequence of making these designs extremely costly. Possibly, more costly than investigating alternative, intrinsically safer designs, which is a somewhat ridiculous situation, is it not? It is also a point of debate as to whether the numerous additional safety features would forestall a pollution release in the event of a serious malfunction. We simply do not know. We are told they would.. but the time we would actually find out is in a genuine emergency.
In the nature of things financial, politicians and investors will always tend to back the sure but unexceptional horse. This leads to the PWR or BWR being the chosen option, because it's been done before, and is a known quantity. Other designs involve a greater financial gamble. Although, at a projected cost of more than fifteen times that of a gasfired powerplant, the proposed new Hinkley Point station is insanely expensive, and is mainly so because of the protective features needed to assuage the doubts over PWR safety.
Perhaps we shall soon see the decision-makers coming to a realisation; that safer might also equal cheaper. The whole R&D cost of developing a molten salt or molten lead cooling system might actually be less than that of building just one intrinsically unsafe and therefore heavily-protected PWR. I can only say that if and when that realisation dawns, it will be a day to celebrate.